The Twitter development team has created and released a custom garbage collector for Ruby Enterprise Edition. It utilizes a dual-heap structure - with transient and long-term heaps - to help reduce CPU load during the routine garbage collection process and increase overall request throughput.

Ryan Sonnek recently released his multitenant gem. This library provides your Rails application with a "with_tenant" block to isolate all nested data queries to a particular tenant's set of data. This should help to enforce data isolation in your multitenant application.

one9 is a command line tool written by Gabriel Horner that helps with your migration from Ruby 1.8 to 1.9. It executes your current application's test suite and records and reports any calls made which will not be compatible with Ruby 1.9.

Vladimir Penkin dropped us a line to let us know about hit TextMate Missing Sidebar library which enhances TextMates current project drawer. It gives you quick access to opening Terminal sessions in the correct location, one-click to GitX, and even resizes your window when the drawer is closed.

SESChange is a library by Stephen Schor. It provides you with a simple Sinatra application that keeps you up to speed on your Amazon SES usage, quotas, delivery attempts, bounces, rejections, complaints, and more.